Unit 2: Cells & Histology A&P Chapter 3.2, Bio 7-3

Movement Across the Cell Membrane A. Cell Membrane

Cell Membranes surround ALL cells!

Controls what molecules ________________________________________________

- food and oxygen molecules must enter the cell

- waste products need to be released

SEMIPERMEABLE – ___________________________________________________

B. Structure of Cell Membrane

Phospholipid bilayer

Polar heads “_______” water (______________)

Nonpolar tails “_______” water (_____________)

C. Fluid Mosaic Model

Describes the _______________________ found in the _______________________

Example:

-____________________: _____________________ and _____________ to move materials across membranes

- ____________________: act like identification cards so cells can identify one another

D. Transport Across a Membrane

Molecules can enter or leave the cell in 2 ways:

◦1. ___________________________

* Diffusion

* Carrier-Facilitated (“helped”) Diffusion

* Osmosis

1. Passive Transport

___________________________________________ across the membrane to occur

Molecules move from area of _______________________________ to area of ____________________________________

Example: Like riding a bike downhill

◦2. ________________________

* Protein Pump

* Endocytosis

* Exocytosis

Unit 2: Cells & Histology A&P Chapter 3.2, Bio 7-3

Two factors determine if passive transport takes place, __________________ and ____________________________

- Equilibrium: when the ____________________ on both sides of the membrane are ____________

- Permeability: ability of a molecule to _________ (move) __________________________________

* ______________________: molecules that cannot pass across a membrane

* semi-permeable/selective permeability: Some molecules can pass across the membrane while other molecules cannot

a. Diffusion

Molecules moving from area of _______________ _______________ to area of ______________________

__________________________ is required

b. Carrier-Facilitated Diffusion

____________________ required

Molecules “__________” across by ________________________ from _________________ concentration

c. Osmosis Osmosis is a special type of diffusion The ____________________ through a selectively permeable membrane

ISOTONIC

_____________ of solutes (dissolved substance) is the _____ in and out of the cell Equal amount of water leaving and entering cell

HYPERTONIC

Solution has a _________ ______________________ than the inside of cell More water ________ cell, causing cell to __________

HYPOTONIC

Solution has a ______________ ___________________________ than the inside of cell More water ____________ cell, causing cell to ________ (get big)

Equilibrium

Unit 2: Cells & Histology A&P Chapter 3.2, Bio 7-3

2. Active TransPort

_____________________ for molecules to pass across

◦_______ – the “battery” of the cell

◦Breaking a bond in ATP releases energy

◦Can “__________” molecules from ____________________________ (against concentration gradient)

Example: Like riding a bike uphill

a. Protein Pump ◦Protein Pumps: cell membrane ________________ and _________ molecule through

◦___________________________

b. Endocytosis

Endocytosis: cell membrane _______________ _______________________ bring it into the cell

Two types:

◦___________________: cytoplasm surrounds a _____________ and packages it in a food _____________

◦______________: cell membrane forms pockets filled with ____________ and pinch off to form ______________________ in a cell

c. Exocytosis

_____________________: The membrane of the vacuole surrounding the material fuses with the cell membrane, ______________________________ _____________________________